Help, my sage is dying D8?

I started growing sage from seed a few weeks ago. It's common sage (salvia officinalis), grew it in a 7 1/2 inch deep pot with that MiracleGro soil stuff. I know sage doesn't need to be watered very often (I've heard it can survive drought conditions, even?) so I haven't overwatered, or at least I don't think so. I water whenever the soil is dry. Right now the soil is damp but the sage plants keep slumping over and leaves are falling off. Am I overwatering or is something else going on? Thank you!